Abstract
The correlation of changes in the electroencephalography (EEG) and cerebral blood flow (CBF) in the parietal cortex and thalamus was studied during 30 minutes of bilateral carotid occlusion (BCO) and following its recirculation in spontaneously hypertensive rats (SHR). A histological examination of the brain was performed in some rats.
Thirty minutes after BCO cortical CBF was reduced from 41.8 ± 4.2 (mean ± SEM) to 4.9 ± 1.7 ml/100 g/min and thalamic CBF from 43.1 ± 2.9 to 21.6 ± 2.2 ml/100 g/min. Cortical EEG was abolished in 12 of 13 rats of which cortical CBF was reduced to 13 ml/100 g/min or below. On the other hand thalamic EEG was abolished in five rats, but in four of these rats thalamic CBF kept more than 20 ml/100 g/min. Following the recirculation, the animals having isoelectric EEG in the cortex or in the thalamus during BCO showed more marked hyperperfusion than did those with either minimal changes or incomplete abolishment of EEG. In the former, however, the improvement of the EEG was poor as compared with that of the latter. Light microscopic examination of the brain revealed mild ischemic changes in the cortex and hippocampus but not in the thalamus.
It was suggested that the CBF reduction leading to altered EEG activity might be different between in the cortex and thalamus, and that severe cortical ischemia could reduce the neuronal activities in the thalamus.
